Image capturing apparatus and capturing method

ABSTRACT

An image capturing apparatus including a plurality of image sensing modules and at least a light source is provided for capturing an image of an eye. Each of the image sensing modules includes an image sensor and a lens. The light source emits an illumination light, and the illumination light irradiates the eye. The eye reflects the illumination light into an image light. The image light includes a plurality of sub-image beams, and the sub-image beams are transmitted to the image sensors of the image sensing modules through the lenses of the image sensing modules, respectively. A capturing method is also provided.

BACKGROUND

1. Technical Field

The invention relates to an image capturing apparatus and a capturingmethod. Particularly, the invention relates to an image capturingapparatus and a capturing method for capturing an eye image.

2. Related Art

The eye is a window to a soul, and through the eyes, people can feellight and color of the world. Cone cells and rod cells in the eye usedfor perceiving lights and color are all located on retina of a fundus,which are unique tissues capable of converting light into physiologicalelectric signals. Blood vessels used for supplying blood and nutrientsto the eye are also located on the fundus. When the fundus has a problemof vessel proliferation or rupture, for example, has symptoms of maculardegeneration and haemorrhage, etc., it is likely to cause death of thecone cells and rod cells on the retina, which may result in loss ofvision of a patient. Therefore, in eye disease diagnosis and preventivehealth care, observation and tracking of images of the fundus are veryimportant.

Generally, limited by a pupil size, in a single one-angle shooting of aconventional fundus image shooting method, even if pupil dilation drugsuch as a mydriatic agent is used, a fundus image range that can becaptured is only a viewing angle of about 30 to 40 degrees. Therefore,if an image of an edge of the fundus is to be captured, the patient isasked to stare a reference point, and then the point where the eyestares is continually moved around in a slow and stable speed, so as tocontinually obtain a plurality of images of the fundus. Then, a dataprocessing device such as a computer, etc. is used to synthesize theimages of the fundus through specific image synthesis software. However,an illumination light used for repeatedly capturing the images of thefundus may also cause discomfort and fatigue of the eye of the patient,which may cause unconscious blink of the eye or nystagmus to influencean image capturing quality. Moreover, since the images of the fundus areobtained through multiple shoots, an exposure value and a white balancefor each shooting are different, and the obtained images need to becorrected before being synthesized by a large-scale calculator such as acomputer, etc., such that difficulty in correction is increased toinfluence the quality of the synthesized image. If the quality of thesynthesized image is influenced, a medical staff is not easy to identifya microvascular image of the fundus, which may cause judgementdifficulty and even delay a timing of treatment of the patient.Therefore, it is important to quickly obtain a complete and clear imageof the fundus.

SUMMARY

The invention is directed to an image capturing apparatus, which iscapable of capturing images of a plurality of different zones of an eye.

The invention is directed to a capturing method, by which a plurality ofimages of an eye are simultaneously captured from different directionsfor synthesis.

An embodiment of the invention provides an image capturing apparatus,which is configured to capture an image of an eye, and the imagecapturing apparatus includes a plurality of image sensing modules and atleast one light source. Each of the image sensing modules includes animage sensor and a lens. The light source emits an illumination light,and the illumination light irradiates the eye. The eye reflects theillumination light into an image light. The image light includes aplurality of sub-image beams, and the sub-image beams are transmitted tothe image sensors of the image sensing modules through the lenses of theimage sensing modules, respectively.

In an embodiment of the invention, the illumination light irradiates afundus of the eye through a pupil of the eye, the fundus reflects theillumination light into the image light, and the sub-image beams of theimage light are respectively transmitted to the image sensing modulesthrough the pupil.

In an embodiment of the invention, image capturing ranges of twoadjacent image sensing modules on the fundus are partially overlapped.

In an embodiment of the invention, optical axes of the lenses of theimage sensing modules are not parallel to each other, and the opticalaxes of the lenses pass through the pupil of the eye.

In an embodiment of the invention, each of the image sensing modulesfurther includes an actuator, which is connected to at least one of theimage sensor and the lens to focus the image sensing module.

In an embodiment of the invention, each of the image sensing modulesfurther includes a micro processing unit, which is electricallyconnected to the corresponding image sensor to obtain data of an imageproduced by the sub-image beam detected by the image sensor.

In an embodiment of the invention, the image capturing apparatus furtherincludes a processing unit, which is electrically connected to the imagesensing modules to synthesize a plurality of images of the eye that arerespectively produced by the sub-image beams detected by the imagesensors.

In an embodiment of the invention, the images of the eye detected by twoof the adjacent image sensors are partially overlapped.

In an embodiment of the invention, the processing unit compares thecoinciding portions of the images to serve as a correction referenceused when the images are synthesized.

In an embodiment of the invention, the processing unit includes a firstcomparison module, a second comparison module, a third comparisonmodule, a fourth comparison module and a determination module. The firstcomparison module compares coinciding portions of a first peripheralimage in the peripheral images and the central image. The secondcomparison module compares coinciding portions of a second peripheralimage in the peripheral images and the central image. The thirdcomparison module calculates an average image of coinciding portions ofthe first peripheral image and the second peripheral image, and comparescoinciding portions of the average image and the central image. Thefourth comparison module calculates a gradient image of the coincidingportions of the first peripheral image and the second peripheral image,and compares coinciding portions of the gradient image and the centralimage. The determination module determines a minimum comparisondifference of comparison results of the first to the fourth comparisonmodules, where when a comparison difference of the first comparisonmodule is the minimum, the determination module uses data of the firstperipheral image for the coinciding portions of the first peripheralimage and the second peripheral image; when a comparison difference ofthe second comparison module is the minimum, the determination moduleuses data of the second peripheral image for the coinciding portions ofthe first peripheral image and the second peripheral image; when acomparison difference of the third comparison module is the minimum, thedetermination module uses data of the average image for the coincidingportions of the first peripheral image and the second peripheral image;and when a comparison difference of the fourth comparison module is theminimum, the determination module uses data of the gradient image forthe coinciding portions of the first peripheral image and the secondperipheral image.

In an embodiment of the invention, the processing unit first performs acorrection of reducing pincushion distortion on the images of the eye,and then synthesizes the images performed with the correction ofreducing pincushion distortion.

An embodiment of the invention provides a capturing method for capturingan image of an eye. The capturing method includes simultaneouslycapturing a plurality of images of the eye from different directions,and synthesizing the images.

In an embodiment of the invention, the images of the eye are a pluralityof images of a fundus of the eye, and the step of simultaneouslycapturing the images of the eye from different directions includescapturing the images of the fundus of the eye through a pupil of theeye.

In an embodiment of the invention, two adjacent images of the fundus ofthe eye are partially overlapped.

In an embodiment of the invention, the step of synthesizing the imagesincludes comparing the coinciding portions of the images to serve as acorrection reference used when the images are synthesized.

In an embodiment of the invention, the correction reference includes atleast one of a color correction reference, a coordinate conversioncorrection reference and a noise reduction correction reference.

In an embodiment of the invention, the images of the eye include acentral image and a plurality of peripheral images adjacent to thecentral image.

In an embodiment of the invention, the step of synthesizing the imagesincludes: (a) comparing coinciding portions of a first peripheral imagein the peripheral images and the central image; (b) comparing coincidingportions of a second peripheral image in the peripheral images and thecentral image; (c) calculating an average image of coinciding portionsof the first peripheral image and the second peripheral image, andcomparing coinciding portions of the average image and the centralimage; (d) calculating a gradient image of the coinciding portions ofthe first peripheral image and the second peripheral image, andcomparing coinciding portions of the gradient image and the centralimage; and (e) determining a minimum comparison difference in comparisonresults of the step (a) to the step (d), where when a comparisondifference of the step (a) is the minimum, data of the first peripheralimage is used for the coinciding portions of the first peripheral imageand the second peripheral image; when a comparison difference of thestep (b) is the minimum, data of the second peripheral image is used forthe coinciding portions of the first peripheral image and the secondperipheral image; when a comparison difference of the step (c) is theminimum, data of the average image is used for the coinciding portionsof the first peripheral image and the second peripheral image; and whena comparison difference of the step (d) is the minimum, data of thegradient image is used for the coinciding portions of the firstperipheral image and the second peripheral image.

In an embodiment of the invention, data of the central image is used fora central zone of the central image, and data of the peripheral imagesis used for portions of a surrounding zone of the central image thatcoincide with the central zones of the adjacent peripheral images.

In an embodiment of the invention, the capturing method further includesperforming a correction of reducing pincushion distortion on the imagesbefore the images are synthesized, where the step of synthesizing theimages is synthesizing the images performed with the correction ofreducing pincushion distortion.

According to the above descriptions, the image capturing apparatusaccording to the embodiments of the invention uses a plurality of imagesensing modules to respectively capture a plurality of images of theeye. In this way, time required for shooting eye images for multipletimes is decreased, and the eye images of a wide viewing angle areobtained. In the capturing method according to the embodiments of theinvention, a plurality of images of the eye can be simultaneouslycaptured from different directions, and the images can be synthesized.By synthesizing the simultaneously captured images, a phenomenon ofuneven brightness and contrast between the images obtained by shootingthe eye for multiple times is avoided, so as to improve efficiency andaccuracy for synthesizing the images.

In order to make the aforementioned and other features and advantages ofthe invention comprehensible, several exemplary embodiments accompaniedwith figures are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1A is a cross-sectional view of an image capturing apparatusaccording to an embodiment of the invention.

FIG. 1B is a front view of the image capturing apparatus in theembodiment of FIG. 1A.

FIG. 1C is a schematic diagram of the image capturing apparatus in theembodiment of FIG. 1A.

FIG. 2 is a block diagram of the image capturing apparatus in theembodiment of FIG. 1A.

FIG. 3 is a schematic diagram of a plurality of overlapped fundus imagesaccording to the embodiment of FIG. 1A.

FIG. 4 is a flowchart illustrating a capturing method according to theembodiment of FIG. 1A.

FIG. 5 is a flowchart illustrating detailed steps of a step S20 of FIG.4.

FIG. 6 is a flowchart illustrating a process of capturing a fundus imageaccording to the embodiment of FIG. 4.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

FIG. 1A is a cross-sectional view of an image capturing apparatusaccording to an embodiment of the invention. FIG. 1B is a front view ofthe image capturing apparatus in the embodiment of FIG. 1A. Referring toFIG. 1A and FIG. 1B, in the present embodiment, the image capturingapparatus 10 is used to capture images of an eye 20. The image capturingapparatus 10 includes a plurality of image sensing modules 100 and atleast one light source 200. Each of the image sensing modules 100includes an image sensor 110 and a lens 120. The image sensor 110 can bea complementary metal-oxide-semiconductor (CMOS) sensor, a chargecoupled device (CCD) or any other optical sensor adapted to receiveimages. Moreover, in the present embodiment, the lens 120 can be drivenby a voice coil motor. In the present embodiment, the image capturingapparatus 10 includes 5 image sensing modules 101, 102, 103, 104 and105, and in other embodiments, the image capturing apparatus 10 mayinclude more or less image sensing modules 100 according to an actualrequirement, which is not limited by the invention. Meanwhile, in thepresent embodiment, the image capturing apparatus 10 includes four lightsources 200, and in other embodiments, the number and distribution ofthe light sources 200 can be designed according to an actual requirementto achieve a purpose of illumination, which is not limited by theinvention. The light source 200 can be a light-emitting diode (LED) orany other suitable light-emitting device, and a light emitted therefromis a visible light or an invisible light such as infrared, etc., whichis not limited by the invention. The light source 200 emits anillumination light L, and the illumination light L irradiates the eye20. The eye 20 reflects the illumination light L into an image light B,and the image light B includes a plurality of sub-image beams BS, andthe sub-image beams BS are respectively transmitted to the image sensors110 through the lenses 120 of the image sensing modules 100.

In detail, in the present embodiment, the illumination light L canirradiate a fundus F of the eye 20 through a pupil P of the eye 20. Thefundus F reflects the illumination light L into the image light B, andthe sub-image beams BS of the image light B are respectively transmittedto the image sensing modules 100 through the pupil P. Image capturingranges of two adjacent image sensing modules 100 on the fundus F arepartially overlapped. Moreover, optical axes X of the lenses 120 of theimage sensing modules 100 can be unparallel to each other, and theoptical axes X of the lenses 120 pass through the pupil P of the eye 20.For example, the image sensing module 101 in FIG. 1A has an optical axisX1, the image sensing module 102 has an optical axis X2, and the imagesensing module 103 has an optical axis X3, where the optical axis X1,the optical axis X2 and the optical axis X3 that are not parallel toeach other passes through the pupil P, such that the image sensingmodule 101, the image sensing module 102 and the image sensing module103 can respectively capture images of different zones on the fundus Ffrom different directions. Namely, the image sensing module 101 cancapture an image of a fundus zone F1, the image sensing module 102 cancapture an image of a fundus zone F2, and the image sensing module 103can capture an image of a fundus zone F3. The fundus zone F1 and thefundus zone F2 are partially overlapped, and the fundus zone F2 and thefundus zone F3 are partially overlapped. In this way, the imagecapturing apparatus 10 can simultaneously capture images of differentzones on the fundus F to aid a medical staff to study more comprehensiveeye image information of a patient, so as to improve accuracy andefficiency of clinical diagnosis of the medical staff.

In detail, referring to FIG. 1A, in the present embodiment, the imagesensing module 100 further includes an actuator 130, which is connectedto at least one of the image sensor 110 and the lens 120 to focus theimage sensing module 100. The actuator 130 can be a voice coil motor(VCM) or other types of motor. For example, in the present embodiment,the actuator 130 can drive the image sensing modules 101, 102 and 103 torespectively focus on the fundus F of the eye 20. As an eye dioptervaries along with people, and even if in a same eye, the diopters ofseeing the fundus from different angles through the pupil are alsodifferent, the actuator 130 is used to respectively control focusing ofeach of the image sensing modules 100, which is adapted to local diopterdifference of the eye and is also adapted to different eyes, so as toshorten a fundus shooting time and improves the image quality.

Moreover, the image sensing module 100 further includes a microprocessing unit 140, which is electrically connected to thecorresponding image sensor 100 to obtain data of an image produced bythe sub-image beam BS detected by the image sensor 100. The microprocessing unit 140 is a microprocessor such as an image signalprocessor (ISP), etc. For example, in the present embodiment, the imagesensing module 101 includes a micro processing unit 141, the imagesensing module 102 includes a micro processing unit 142, and the imagesensing module 103 includes a micro processing unit 143. Namely, each ofthe image sensing modules 100 may have the respective micro processingunit 140 to serve as a fundus image processing sub-system. Moreover, theimage capturing apparatus 100 may further include a processing unit 150,which is electrically connected to the image sensing modules 100 tosynthesize a plurality of images of the eye 20 that are respectivelyproduced by the sub-image beams BS detected by the image sensors 110.The processing unit 150 can be a digital signal processor (DSP). Forexample, referring to FIG. 2, in the present embodiment, the imagesensing modules 101, 102, 103, 104 and 105 respectively have thecorresponding micro processing units 141, 142, 143, 144 and 145, and theimage sensing modules 101, 102, 103, 104 and 105 also have correspondingrandom access memories (RAMs) RAM1, RAM2, RAM3, RAM4 and RAM5 to storeimage information processed by the micro processing units 141, 142, 143,144 and 145. Moreover, the processing unit 150 may synthesize imageinformation coming from the image sensing modules 101, 102, 103, 104 and105 and processed by the micro processing unit 140, and may store asynthesized result or computed data in a memory unit SR, where thememory unit SR is, for example, a synchronous dynamic random accessmemory (SDRAM). Therefore, image synthesis efficiency is effectivelyincreased and a high cost caused by using a fast processor is saved.Meanwhile, in the present embodiment, since the micro processing unit140 used in collaboration with the processing unit 150 can reduce thefundus shooting time, fundus images of different zone captured fromdifferent angles can be continuously processed, and the synthesizedfundus image can be displayed on a display unit DU, such that the imagecapturing apparatus 10 may have a live view function to assist focusingthe fundus image, so as to improve efficiency and accuracy forsynthesizing the images.

In detail, referring to FIG. 1A, FIG. 1B and FIG. 3, in the presentembodiment, the images of the eye 20 detected by two adjacent imagesensors 110 are partially overlapped, and the images of the eye 20 mayinclude a central image P0 and a plurality of peripheral images Padjacent to the central image P0. The processing unit 150 may comparethe coinciding portions of the images to serve as a correction referenceused when the images are synthesized. The correction reference includesat least one of a color correction reference, a coordinate conversioncorrection reference and a noise reduction correction reference. Indetail, referring to FIG. 1A, FIG. 1C and FIG. 3, the processing unit150 may include a first comparison module M1, a second comparison moduleM2, a third comparison module M3, a fourth comparison module M4 and adetermination module MJ. The first comparison module M1 comparescoinciding portions of a first peripheral image P1 in the peripheralimages P and the central image P0, i.e. compares data of the firstperipheral image P1 in a coinciding zone P01 (i.e. a zone drawn withoblique lines) with data of the central image P0 in the coinciding zoneP01. The second comparison module M2 compares coinciding portions of asecond peripheral image P2 in the peripheral images P and the centralimage P1, i.e. compares data of the second peripheral image P2 in acoinciding zone P02 (i.e. a zone drawn with cross lines) with data ofthe central image P0 in the coinciding zone P02. The third comparisonmodule M3 calculates an average image of coinciding portions of thefirst peripheral image P1 and the second peripheral image P2, andcompares coinciding portions of the average image and the central imageP0, i.e. after averaging data of the first peripheral image P1 in acoinciding zone P12 (a zone simultaneously drawn with oblique lines andcross lines) and data of the second peripheral image P2 in thecoinciding zone P12, the third comparison module M3 compares theaveraged data with data of the central image P0 in the coinciding zoneP12. The fourth comparison module M4 calculates a gradient image of thecoinciding portions of the first peripheral image P1 and the secondperipheral image P2, and compares coinciding portions of the gradientimage and the central image P0, i.e. after performing gradient imagecomputation on data of the first peripheral image P1 in the coincidingzone P12 and data of the second peripheral image P2 in the coincidingzone P12, the fourth comparison module M4 compares data of a computationresult thereof with data of the central image P0 in the coinciding zoneP12. The determination module MJ determines a minimum comparisondifference of comparison results of the first to the fourth comparisonmodules M1, M2, M3 and M4, where when a comparison difference of thefirst comparison module M1 is the minimum, the determination module MJuses data of the first peripheral image P1 for the coinciding portionsof the first peripheral image P1 and the second peripheral image P2.When a comparison difference of the second comparison module M2 is theminimum, the determination module MJ uses data of the second peripheralimage P2 for the coinciding portions of the first peripheral image P1and the second peripheral image P2. When a comparison difference of thethird comparison module M3 is the minimum, the determination module MJuses data of the average image for the coinciding portions of the firstperipheral image P1 and the second peripheral image P2. When acomparison difference of the fourth comparison module M4 is the minimum,the determination module MJ uses data of the gradient image for thecoinciding portions of the first peripheral image P1 and the secondperipheral image P2. In this way, the images received by the imagesensing module 100 can be synthesized in a manner of the minimumdifference and the most correct content. Generally the central image P0is an image close to a central zone of the fundus F, which has adistortion such as a pincushion distortion smaller than that of theimage at a zone away from the central zone of the fundus F, which iseasy to be corrected. As the central image P0 is taken as a referenceimage, and errors of the central image P0 and the other peripheralimages P are referred to synthesize the images of the fundus F, accuracyof image synthesis is further enhanced. The number of the peripheralimages P illustrated in FIG. 3 is only used as an example; the actuallycomputed images can be different according to the number of the actuallycaptured images, which is not limited by the invention.

Moreover, in the present embodiment, the central image P0 is partiallyoverlapped with the peripheral images P (which are, for example, thefirst peripheral image P1, the second peripheral image P2, the thirdperipheral image P3 and the fourth peripheral image P4, and in otherembodiments, the number of the peripheral images can be increased ordecreased according to an actual requirement, which is not limited bythe invention). Since the human eye has diopter, in the image of thefundus F, an image distortion at an outer edge of the image is obviouscompared to that at a central portion. In the present embodiment, theprocessing unit 150 may use data of the central image P0 for a centralzone CZ of the central image P0, and the processing unit 150 may usedata of the peripheral images P for coinciding portions of thesurrounding zone SZ of the central image P0 and the central zones CZ ofthe peripheral images P. Namely, when the images of the fundus F aresynthesized, it is better to use the central portion of a single fundusimage as far as possible, and avoid using the zone at the outer edge ofthe image that has an obvious image distortion. In the presentembodiment, since the processing unit 150 can first perform a correctionof reducing pincushion distortion on the images of the eye 20 forsubsequent synthesis, particularly on an outer edge portion of the imagethat has a severe image distortion, the manner of correcting thepincushion distortion can generally add extra image points to compensateresolution decrease caused by the correction. Therefore, the method ofavoiding using the image edge to synthesize the images of the fundus Fcan mitigate decrease of image quality caused by the additionally addedimage points.

The first comparison module M1, the second comparison module M2, thethird comparison module M3, the fourth comparison module M4 and thedetermination module MJ can be programs stored in a storage medium ofthe image capturing apparatus 10, which can be located into theprocessing unit 150 to execute the aforementioned functions.Alternatively, in other embodiments, the first comparison module M1, thesecond comparison module M2, the third comparison module M3, the fourthcomparison module M4 and the determination module MJ can also behardware devices composed of logic circuit components, which can be usedto execute the aforementioned functions.

FIG. 4 is a flowchart illustrating a capturing method according to anembodiment of the invention. Referring to FIG. 1A, FIG. 3 and FIG. 4, inthe present embodiment, the capturing method is used to capture an imageof the eye 20. The capturing method includes simultaneously capturing aplurality of images P of the eye 20 from different directions (stepS10). The capturing method further includes synthesizing the images P(step S20). The images P of the eye 20 are a plurality of images P ofthe fundus F of the eye 20, and the step S10 of simultaneously capturingthe images P of the eye 20 from different directions includes capturingthe images P of the fundus F of the eye 20 through a pupil P of the eye20. In this way, the simultaneously captured images of the fundus F havesimilar brightness and contrasts, which avails the subsequent imagesynthesis, and saves a computation time of the image synthesis andimproves the quality of the synthesized image, and avails the clinicaldiagnosis of eye diseases.

The images of the fundus F of the eye 20 include the central image P0and a plurality of peripheral images P adjacent to the central image P0.Moreover, the step S20 of synthesizing the images may include comparingthe coinciding portions of the images to serve as a correction referenceused when the images are synthesized. Moreover, in the presentembodiment, before synthesizing the images, the capturing method furtherincludes performing a correction of reducing pincushion distortion onthe images (step S10 a), where the step S20 of synthesizing the imagesis to synthesize the images performed with the correction of reducingpincushion distortion, and the effect of synthesizing the images is asthat described in the embodiment of FIG. 1A, which is not repeated.

In detail, referring to FIG. 5, the step S20 of synthesizing the imagesincludes: (a) comparing coinciding portions of a first peripheral imageP1 in the peripheral images P and the central image P0 (step S20 a); (b)comparing coinciding portions of a second peripheral image P2 in theperipheral images P and the central image P0 (step S20 b); (c)calculating an average image of coinciding portions of the firstperipheral image P1 and the second peripheral image P2, and comparingcoinciding portions of the average image and the central image P0 (stepS20 c); (d) calculating a gradient image of the coinciding portions ofthe first peripheral image P1 and the second peripheral image P2, andcomparing coinciding portions of the gradient image and the centralimage P0 (step S20 d); and (e) determining a minimum comparisondifference in comparison results of the step (a) to the step (d) (stepS20 e). In detail, when a comparison difference of the step (a) is theminimum, data of the first peripheral image P1 is used for thecoinciding portions of the first peripheral image P1 and the secondperipheral image P2; when a comparison difference of the step (b) is theminimum, data of the second peripheral image P2 is used for thecoinciding portions of the first peripheral image P1 and the secondperipheral image P2; when a comparison difference of the step (c) is theminimum, data of the average image is used for the coinciding portionsof the first peripheral image P1 and the second peripheral image P2;when a comparison difference of the step (d) is the minimum, data of thegradient image is used for the coinciding portions of the firstperipheral image P1 and the second peripheral image P2. Data of thecentral image P0 is used for the central zone CZ of the central imageP0, and data of the peripheral images P is used for coinciding portionsof the surrounding zone SZ of the central image P0 and the central zonesCZ of the peripheral images P. Detailed process and effect ofsynthesizing the images are as that described in the embodiment of FIG.1A. The step (a) to the step (e) can be executed by the first comparisonmodule M1, the second comparison module M2, the third comparison moduleM3, the fourth comparison module M4 and the determination module MJ, anddetails thereof can refer to descriptions of the functions executed bythese modules, which are not repeated. Moreover, the sequence of theaforementioned steps is only used as an example, which is not limited bythe invention.

For example, referring to FIG. 6, in the present embodiment, the flow ofshooting the fundus images may includes following steps. The pupil P isautomatically detected (step S5), and it is determined whether the pupilP is detected (step S6), and if an image of the pupil P is not detected,the step S5 of detecting the pupil P is repeated. If the image of thepupil P is detected, a plurality of images of the eye 20 aresimultaneously captured from different directions (step S10), and thelenses 120 are driven to focus (step S11). Then, the lenses 120 (forexample, N lenses 120 of a lens 1, a lens 2, . . . , and a lens N, whereN is a positive integer greater than 1) on the image sensing module 100can respectively focus (step S12), and it is determined whether thefocus is successful (step S13). If the focus is not successful, the stepS12 is returned to again focus. After all of the lenses 120 (includingthe lenses 120 located at the central portion and peripheral portion ofthe image sensing apparatus 10) complete focusing (step S14), the imagesensing module 100 is driven to capture images (step S15). The imagesensing module 100 and the lens 120 can be used to capture images of thefundus F (step S16). Then, the processing unit 150 is used to synthesizethe images (step S20) to output the fundus images (step S30). In thisway, the image sensing apparatus 10 can automatically detectphysiological information of human eye, and output a large-range andclear fundus image to facilitate medical staff to diagnose.

In summary, the image capturing apparatus according to the embodimentsof the invention can be used to simultaneously capture a plurality offundus images of different portions of the eye, and since the fundusimages can be nearly simultaneously captured, the brightness and thecontrasts thereof are similar. Then, the processing unit is used tocompare differences of the coinciding portions of the fundus images, andthe fundus images are synthesized in a manner of the minimum differencebetween the images, which may effectively save a time required forsynthesizing the images, and quickly obtain the fundus images with alarge range and good image quality. Moreover, each of the image sensingmodules may include an actuator, by which the image sensing modules cansimultaneously focus on different zones of the fundus from differentangles, which may save a time required for capturing the eye images,decrease an eye burden of a patient and increase a success rate ofcapturing the large-range and clear fundus image, so as to improvemedical quality and diagnosis accuracy of the medical staff.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of theinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the invention covermodifications and variations of this invention provided they fall withinthe scope of the following claims and their equivalents.

What is claimed is:
 1. An image capturing apparatus, configured tocapture an image of an eye, the image capturing apparatus comprising: aplurality of image sensing modules configured to simultaneously capturea plurality of images of a fundus of the eye from different directions,each comprising an image sensor and a lens, wherein the images of thefundus of the eye comprise a central image and a plurality of peripheralimages adjacent to the central image, and the central image is partiallyoverlapped with each of the peripheral images and each overlappingportions between two peripheral images; at least one light source,emitting an illumination light, wherein the illumination lightirradiates the eye, and the eye reflects the illumination light into animage light, the image light comprises a plurality of sub-image beams,and the sub-image beams are respectively transmitted to the imagesensors through the lenses of the image sensing modules; and aprocessing unit, electrically connected to the image sensing modules tosynthesize a plurality of images of the eye that are respectivelyproduced by the sub-image beams detected by the image sensors, whereinthe processing unit comprises: a first comparison module, comparingcoinciding portions of a first peripheral image in the peripheral imagesand the central image; a second comparison module, comparing coincidingportions of a second peripheral image in the peripheral images and thecentral image; a third comparison module, calculating an average imageof coinciding portions of the first peripheral image and the secondperipheral image, and comparing coinciding portions of the average imageand the central image; a fourth comparison module, calculating agradient image of the coinciding portions of the first peripheral imageand the second peripheral image, and comparing coinciding portions ofthe gradient image and the central image; and a determination module,determining a minimum comparison difference of comparison results of thefirst to the fourth comparison modules, wherein when a comparisondifference of the first comparison module is the minimum, thedetermination module uses data of the first peripheral image for thecoinciding portions of the first peripheral image and the secondperipheral image; when a comparison difference of the second comparisonmodule is the minimum, the determination module uses data of the secondperipheral image for the coinciding portions of the first peripheralimage and the second peripheral image; when a comparison difference ofthe third comparison module is the minimum, the determination moduleuses data of the average image for the coinciding portions of the firstperipheral image and the second peripheral image; and when a comparisondifference of the fourth comparison module is the minimum, thedetermination module uses data of the gradient image for the coincidingportions of the first peripheral image and the second peripheral image.2. The image capturing apparatus as claimed in claim 1, wherein theillumination light irradiates the fundus of the eye through a pupil ofthe eye, the fundus reflects the illumination light into the imagelight, and the sub-image beams of the image light are respectivelytransmitted to the image sensing modules through the pupil.
 3. The imagecapturing apparatus as claimed in claim 2, wherein image capturingranges of two adjacent image sensing modules on the fundus are partiallyoverlapped.
 4. The image capturing apparatus as claimed in claim 1,wherein optical axes of the lenses of the image sensing modules are notparallel to each other, and the optical axes of the lenses pass throughthe pupil of the eye.
 5. The image capturing apparatus as claimed inclaim 1, wherein each of the image sensing modules further comprises anactuator connected to at least one of the image sensor and the lens tofocus the image sensing module.
 6. The image capturing apparatus asclaimed in claim 5, wherein each of the image sensing modules furthercomprises a micro processing unit electrically connected to thecorresponding image sensor to obtain data of an image produced by thesub-image beam detected by the image sensor.
 7. The image capturingapparatus as claimed in claim 1, wherein the images of the eye detectedby two of the adjacent image sensors are partially overlapped.
 8. Theimage capturing apparatus as claimed in claim 7, wherein the processingunit compares coinciding portions of the images to serve as a correctionreference used when the images are synthesized.
 9. The image capturingapparatus as claimed in claim 8, wherein the correction referencecomprises at least one of a color correction reference, a coordinateconversion correction reference and a noise reduction correctionreference.
 10. The image capturing apparatus as claimed in claim 7,wherein the processing unit uses data of the central image for a centralzone of the central image, and the processing unit uses data of theperipheral images for portions of a surrounding zone of the centralimage that coincide with central zones of the adjacent peripheralimages.
 11. The image capturing apparatus as claimed in claim 1, whereinthe processing unit first performs a correction of reducing pincushiondistortion on the images of the eye, and then synthesizes the imagesperformed with the correction of reducing pincushion distortion.
 12. Acapturing method, configured to capture an image of an eye, thecapturing method comprising: simultaneously capturing a plurality ofimages of a fundus of the eye from different directions, wherein theimages of the fundus of the eye comprise a central image and a pluralityof peripheral images adjacent to the central image, and the centralimage is partially overlapped with each of the peripheral images andeach overlapping portions between two peripheral images; andsynthesizing the images, wherein the step of synthesizing the imagescomprises comparing coinciding portions of the images to serve as acorrection reference used when the images are synthesized, and the stepof synthesizing the images further comprises: (a) comparing coincidingportions of a first peripheral image in the peripheral images and thecentral image; (b) comparing coinciding portions of a second peripheralimage in the peripheral images and the central image; (c) calculating anaverage image of coinciding portions of the first peripheral image andthe second peripheral image, and comparing coinciding portions of theaverage image and the central image; (d) calculating a gradient image ofthe coinciding portions of the first peripheral image and the secondperipheral image, and comparing coinciding portions of the gradientimage and the central image; and (e) determining a minimum comparisondifference in comparison results of the step (a) to the step (d),wherein when a comparison difference of the step (a) is the minimum,data of the first peripheral image is used for the coinciding portionsof the first peripheral image and the second peripheral image; when acomparison difference of the step (b) is the minimum, data of the secondperipheral image is used for the coinciding portions of the firstperipheral image and the second peripheral image; when a comparisondifference of the step (c) is the minimum, data of the average image isused for the coinciding portions of the first peripheral image and thesecond peripheral image; and when a comparison difference of the step(d) is the minimum, data of the gradient image is used for thecoinciding portions of the first peripheral image and the secondperipheral image.
 13. The capturing method as claimed in claim 12,wherein the step of simultaneously capturing the images of the fundus ofthe eye from different directions comprises capturing the images of thefundus of the eye through a pupil of the eye.
 14. The capturing methodas claimed in claim 13, wherein two adjacent images of the fundus of theeye are partially overlapped.
 15. The capturing method as claimed inclaim 12, wherein the correction reference comprises at least one of acolor correction reference, a coordinate conversion correction referenceand a noise reduction correction reference.
 16. The capturing method asclaimed in claim 14, wherein data of the central image is used for acentral zone of the central image, and data of the peripheral images isused for portions of a surrounding zone of the central image thatcoincide with the central zones of the adjacent peripheral images. 17.The capturing method as claimed in claim 12, further comprising:performing a correction of reducing pincushion distortion on the imagesbefore the images are synthesized, wherein the step of synthesizing theimages is synthesizing the images performed with the correction ofreducing pincushion distortion.